HashCode hashCode1 = Hashing.combineOrdered(hashCodes);
    Collections.shuffle(hashCodes, random);
    HashCode hashCode2 = Hashing.combineOrdered(hashCodes);

    assertFalse(hashCode1.equals(hashCode2));
  }

  public void testCombineUnordered_empty() {
    assertThrows(
        IllegalArgumentException.class,
        () -> Hashing.combineUnordered(Collections.<HashCode>emptySet()));
  }

import static com.google.common.collect.testing.Helpers.assertEqualInOrder;
import static com.google.common.collect.testing.Helpers.testComparator;
import static java.util.Arrays.asList;
import static java.util.Collections.emptyIterator;
import static java.util.Collections.singleton;

import com.google.common.annotations.GwtCompatible;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;

import com.google.common.collect.testing.features.CollectionSize;
import com.google.common.collect.testing.features.Feature;
import com.google.common.collect.testing.features.ListFeature;
import java.util.Collections;
import java.util.EnumSet;
import java.util.List;
import java.util.Map.Entry;
import java.util.Set;
import junit.framework.TestSuite;

/**

import static com.google.common.collect.testing.Helpers.assertEqualInOrder;
import static com.google.common.collect.testing.Helpers.testComparator;
import static java.util.Arrays.asList;
import static java.util.Collections.emptyIterator;
import static java.util.Collections.singleton;

import com.google.common.annotations.GwtCompatible;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;

package com.google.common.collect;

import static com.google.common.collect.BoundType.CLOSED;
import static com.google.common.truth.Truth.assertThat;
import static java.util.Arrays.asList;
import static java.util.Collections.sort;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.J2ktIncompatible;

import java.util.Collection;
import java.util.List;
import org.jspecify.annotations.NullMarked;

/**
 * Creates collections containing unhashable sample elements, to be tested.
 *
 * @author Regina O'Dell
 */
@GwtCompatible
@NullMarked
public abstract class TestUnhashableCollectionGenerator<T extends Collection<UnhashableObject>>

   * half of that is more awkward to arrange...
   */
  private static <T> Iterable<T> iterable(Collection<T> collection) {
    // return collection::iterator;
    return new Iterable<T>() {
      @Override
      public Iterator<T> iterator() {
        return collection.iterator();
      }
    };
  }

  public void testEquals() {
    new EqualsTester()

import com.google.common.collect.testing.features.CollectionFeature;
import com.google.common.testing.SerializableTester;
import org.junit.Ignore;

/**
 * Basic reserialization test for collections.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
@Ignore("test runners must not instantiate and run this directly, only via suites we build")

import com.google.common.collect.testing.SortedSetTestSuiteBuilder;
import com.google.common.collect.testing.features.CollectionSize;
import com.google.common.collect.testing.features.Feature;
import java.util.Collections;
import java.util.EnumSet;
import java.util.List;
import java.util.Map.Entry;
import java.util.Set;
import junit.framework.TestSuite;

/**

import static com.google.common.truth.Truth.assertThat;
import static java.util.Arrays.asList;
import static java.util.Collections.emptyList;
import static java.util.Collections.emptySet;
import static java.util.Collections.singleton;
import static java.util.Collections.singletonList;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;